The attack worked, the password is cmF0dGEK
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This was obtained by generating 32 possible plaintexts for the first 10 bytes of system.zip (based on the different values in the headers of ~300 zip files on my system), plus three null bytes for the high bytes of compressed size, file name length and extra field length.
This is possible, after all, legwork.i2p is based on YaCy. I’d recommend taking a look at the YaCy and Tor guide, and use it as a template. Where they create a Tor hidden service, create an I2P server tunnel, and where they proxy YaCy to Privoxy just proxy directly to I2P’s HTTP proxy.